Abstract
A methods framework is presented that utilizes field plots, airborne light detection and ranging (LiDAR), and spaceborne Geoscience Laser Altimeter System (GLAS) data to estimate forest attributes over a 20 Mha area in Northern Canada. The framework was implemented to scale up forest attribute models from field data to intersecting airborne LiDAR data, and then to GLAS footprints. GLAS data were sequentially filtered and submitted to the k-nearest neighbour (k-NN) imputation algorithm to yield regional estimates of stand height and crown closure at a 30 m resolution. Resulting outputs were assessed against independent airborne LiDAR data to evaluate regional estimates of stand height (mean difference = −1 m, RMSE = 5 m) and crown closure (mean difference = −5%, RMSE = 9%). Additional assessments were performed as a function of dominant vegetation type and ecoregion to further evaluate regional products. These attributes form the primary descriptive structure attributes that are typical of forest inventory mapping programs, and provide insight into how they can be derived in northern boreal regions where field information and physical access is often limited.
Highlights
The health and sustainability of boreal forests are of increasing concern, with evidence that the circumboreal regions of the planet are warming and sensitive to changes in climate [1,2,3]
A simple linear function based on the areal light detection and ranging (LiDAR) p95 metric was selected as the best predictor of field measured stand height (Table 3)
Model fit statistics for both stand height and crown closure were indicative of model performance as noted by the similarity between the magnitudes of root mean square error (RMSE) and the resulting cross-validation mean prediction error
Summary
The health and sustainability of boreal forests are of increasing concern, with evidence that the circumboreal regions of the planet are warming and sensitive to changes in climate [1,2,3]. This information has traditionally been based on the interpretation of analogue and digital aerial photographs combined with field and aerial surveys [10,11,12] Such methods are impractical to apply over vast, inaccessible forested areas in northern boreal regions such as the Northwest Territories (NWT) where forests are distributed across 40 Mha of land. Existing inventory data are sparse and inconsistent due to varying vintage, and to changes in data definitions and measurement standards that necessitate an investigation of new data sources and methods [13] This reality is consistent with previous reports that inventory data are often out of date or not available for large regions of the boreal [14]. Being able to generate periodic inventories across large areas would help monitor the state of forested areas across the boreal for multiple objectives such as wood production, climate change mitigation and biodiversity conservation [17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
